Fast Slip Velocity in a High-Entropy Alloy
Due to fluctuations in nearest-neighbor distances and chemistry within the unit cell, high-entropy alloys are believed to have a much higher resistance to dislocation motion than pure crystals. Here, we investigate the coarse-grained dynamics of a number of dislocations being active during a slip event. We found that the time-resolved dynamics of slip is practically identical in Au〈001〉 and an Al0.3CoCrFeNi〈001〉 high-entropy alloy, but much faster than in Nb〈001〉. Differences between the FCC-crystals are seen in the spatiotemporal velocity profile, with faster acceleration and slower velocity relaxation in the high-entropy alloy. Assessing distributions that characterize the intermittently evolving plastic flow reveals material-dependent scaling exponents for size, duration, and velocity–size distributions. The results are discussed in view of the underlying dislocation mobility.
This research was carried out in part in the Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois. G.S. and R.M. especially thank Kathy Walsh for experimental support with the Hysitron TriboIndenter. R.M. would like to thank P.M. Derlet for fruitful discussions, and is grateful for financial support by the NSF CAREER program (grant NSF DMR 1654065), and for start-up funds provided by the Department of Materials Science and Engineering at UIUC. The authors also thank P. Liaw for providing the HEA.
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